Thread: Plastic dowels and Head gasket problems

Originally Posted by Ean Austral

Gday all,am wondering why the dowels in the td5 head would cause the so-called head gasket problems.Been reading with interest about this as mine is getting up there in the kms (215k).
I thought the dowels were only to locate the head upon fitting,if this is so, is it a case of the head bolts loosing tension.Im leaning towards the..If it aint broke dont touch it idea..but with some remote trips coming up cant help but wonder about this one.
Thanks and Cheers Ean

Sorry i cant comment , ive been banned from answering posts about head gaskets so ive been told
But i like tempting fate so im with you
Sorrt JC

Originally Posted by rangieman

Sorry i cant comment , ive been banned from answering posts about head gaskets so ive been told
But i like tempting fate so im with you
Sorrt JC

Good one Chris!


The problem exists with the plastic dowels deforming/ breaking mainly due to overheating etc and this causes the head to shift, and thereby breaking the sealing of nthe fire rings and causing gasses to creep under the fire ring and pressurise the cooling system. The Td5 is especially prone to this as the head gasket is steel shim type and actually bites into the ally of the head to help seal, and the cooling passageways are incredibly close to the edge of the cylinder anyway, which leaves very little room for error.

Later ones (2001 on) had steel locating dowels, and I have yet to have a problem with any of this age, except for those that get REALLY hot and crack/ warp the head but that can happen to any vehicle IME if it gets hot enough.

The banter that Chris (Rangieman)and I have is about replacing a head gasket before it fails, I'm a preventative maintenance type, whereas Chris is a 'living on the edge' sort of person.

JC

Thanks for the replys,you say 2001 on had steel ones,do you know if there is a way thru VIN# to tell if you have the steel or not? Mine is late 2001 according to the plate but it has the CDL and they we supposedly only fitted tolate 2000 models.
Have had the car since 5k and know its history so will keep an eye on it.
thanks and Cheers Ean

I haven't got the actual VIN range numbers, but I suggest that late '01 should be safe.

JC

My Oct 02 build has plastic dowels according to the VIN, but I no longer have recorded the VIN where steel dowels commenced.

the plastic dowels locate the head during assembley and thats it.

If the head walks around there is another problem afoot.

the headbolts keep the head in place.

Hmmm might be also worthwhile double checking that if the head does come off and you have plastic dowels will the metal ones fit?????

A little voice...one of many... in the back of my head says they are different sizing.

Early heads wont take the steel dowels that are used to replace the plastic ones in later heads. I made steel ones for my '99 using the shank of an 8mm drill bit, having purchased some new plastic ones to obtain the required length then made the steel ones about 2mm shorter.